Tips on ICD-9-CM Coding
for Chronic Kidney Disease

In October 2005, the Centers for Medicare & Medicaid Services (CMS) issued revised ICD-9-CM coding rules for chronic kidney disease (CKD). However, many physician offices continue to use the outdated codes or code incompletely.

ICD-9-CM coding is the most critical piece of information on a Medicare claim or encounter. Medicare reimbursement is based on the Hierarchical Condition Category (HCC) model, which relies on ICD-9-CM diagnosis codes. Medicare requires all claims and encounters to be coded to the highest level of specificity, including coding for all secondary diagnoses.

A summary of the revised coding practices for CKD is provided below. Please ensure that your staff members who are responsible for coding are aware of this information and that all charge description masters are updated accordingly.

Chronic kidney disease
Most cases of CKD must be represented by codes from two separate ICD-9-CM categories: category 585, which carries the code descriptor "chronic kidney disease," and either category 403, "hypertensive chronic kidney disease," or category 404, "hypertensive heart and chronic kidney disease." These category code descriptors were changed as part of the October 2006 update.

The category 585 code is used to indicate the diagnosis of CKD and the stage or manifestation of the disease. Categories 403 or 404 are used to describe the patient's hypertension as it relates to CKD.

Category 585 – Chronic kidney disease
There are seven fourth-digit subcategories for use with category 585. These fourth-digit subcategories, shown in the table below, are used to reflect the revised staging guidelines for CKD. The stages of CKD are based on the glomerular filtration rate (GFR). The table outlines how GFR rates correlate with the stages of CKD. Note that the code for chronic renal insufficiency is 585.9.

When documenting an encounter with a member with CKD, physicians should always note the member's GFR or CKD stage. The coder relies on the physician's documentation to determine the stage, and therefore, the appropriate code.

Categories 403 and 404
In addition to the code from the 585 category, coders must use a code from the 400 series to indicate the state of the member's hypertension. Most members with CKD warrant the use of a code from category 403 or 404. The code descriptors for these categories were changed in the October 2006 update to the following:

• Category 403 is titled "hypertensive chronic kidney disease."
• Category 404 is titled "hypertensive heart and chronic kidney disease."

The ICD-9-CM coding model assumes a relationship between hypertension and CKD. Therefore, codes from either category 403 or 404 would always be used, unless the physician believes that the member's hypertension has no connection to CKD. In this case, the coder would indicate the member's hypertension with another appropriate ICD-9-CM code from the 400 series (i.e., 401, essential hypertension; or 402, hypertensive heart disease.)

Code categories 403 and 404 both require the use of a fourth and a fifth digit. The fourth digit in categories 403 and 404 indicates whether the patient's hypertension is:

• malignant (0)
• benign (1), or
• unspecified (9).

For example, hypertensive CKD, benign, would be represented with code 403.1. The code for hypertensive heart and CKD, unspecified, would be 404.9.

Each category has unique subcategories for the fifth digit.

The fifth-digit subcategories for 403 are as follows:

• CKD stage I through stage IV or unspecified (0)
• CKD stage V or ESRD (1)

For example, hypertensive CKD, benign, ESRD, would be represented with code 403.11.

The fifth-digit subcategories for 404 are:

• without heart failure and with CKD stage I through stage IV or unspecified (0)
• with heart failure and with CKD stage I through stage IV or unspecified (1)
• without heart failure and with CKD stage V or ESRD (2)
• with heart failure and with CKD stage V or ESRD (3)

For example, the code for hypertensive heart and CKD, unspecified, without heart failure, would be 404.90.

To learn more about ICD-9-CM coding, visit the CMS Web site at www.cms.gov. Humana also provides an electronic coding tool to help physician offices use ICD-9-CM codes effectively. Physicians can download an Excel® version of this tool to their personal computer or personal digital assistant (PDA) at Humana.com. The download includes all diagnosis codes under the specified condition categories. To download the electronic coding tool from the provider home page, click on "Plans and Products." Select "Medicare," then click on the "Individual Medicare" or "Group Medicare" link. From the right side column, click on "Find Plans." Enter your ZIP code, and then select the appropriate Medicare Advantage plan from the drop-down menu. The page that follows includes links to more information on the CMS-HCC Medicare risk adjustment model and to the free Medicare Risk Adjustment (MRA) ICD-9-CM coding tool.

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